Sound is processed in our inner ear hair cells as a mechanosensory stimulus to stereocilia, protrusions on the surface of the cells. These stereocilia are made up of a very ordered array of interconnected actin filaments, and our hearing is dependent on this precise structure. TRIOBP, a protein that when mutated causes a form of human deafness, was recently found to play an important role in bundling the actin filaments in stereocilia. Electron microscopy images above show mouse inner ear hair cells lacking TRIOBP, with (left) or without (right) the links that interconnect stereocilia to one another. This experiment was used to test whether or not these extracellular links regulate the stiffness of the stereocilia, which would in turn affect hearing.
Reference: Shin-ichiro Kitajiri, Takeshi Sakamoto, Inna A. Belyantseva, Richard J. Goodyear, Ruben Stepanyan, Ikuko Fujiwara, Jonathan E. Bird, Saima Riazuddin, Sheikh Riazuddin, Zubair M. Ahmed, Jenny E. Hinshaw, James Sellers, James R. Bartles, John A. Hammer III, Guy P. Richardson, Andrew J. Griffith, Gregory I. Frolenkov and Thomas B. Friedman. Cell 141, 786-798. ©2010 Elsevier Ltd All rights reserved. Paper can be found here.